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I'm working through the "20 Intermediate Exercises" that give Functors and Monads and such cute, non-threatening names and ask you to implement them. I've gotten most of the way through, with three or four that I'm stuck on--that's under the assumption that the inductive step from banana to banana2 will make the rest of the banana<n> obvious. (If you have sausage, it's easy to implement moppy, and vice versa, but avoiding circularity is the issue.)

So... I did a Bad Thing and looked at solutions a couple of people have posted, saying to myself, "OK, I'll look at those I've already done with an eye to more elegant expression, and look at the ones I'm having issues with and make sure I understand"... and came face to face with a question about composition.

<andy_rooney>Didja ever notice that the examples of composition you see are what we think of as functions with one argument?</andy_rooney> Well, one of the solution…